1. Field of the Invention
The present invention generally relates to communications systems and, in particular, to a system and method for enciphering and communicating vehicle tracking information to a base station that notifies a user of a particular location of a vehicle.
2. Related Art
A vehicle tracking system is disclosed in co-pending U.S. Patent Application entitled xe2x80x9cAdvance Notification Systems and Methods Utilizing a Computer Network,xe2x80x9d filed May 6, 1997, and assigned Ser. No. 08/852,119, which is incorporated herein by reference. In this system, each vehicle is equipped with a sensor (e.g., a global positioning system (GPS) sensor) to determine the vehicle""s location relative to a predetermined reference point. For example, in using GPS technology, each sensor receives signals from GPS satellites indicating the global latitude and longitude coordinate values of the sensor from the Earth""s zero degree latitude and zero degree longitude location (i.e., at the intersection of the equator and the prime meridian). Typically, the latitude coordinate value and the longitude coordinate value transmitted from the GPS satellite are each thirty-two bit words of digital data.
Each vehicle associated with the tracking system transmits its location (i.e., transmits the thirty-two bit coordinate values received from the GPS satellite) and other information to a base station. The base station includes a processor to receive the coordinate values of each vehicle and to monitor the location and status of each vehicle. When the travel data communicated from a particular vehicle indicates that the vehicle reached a predetermined location (e.g., a certain distance from a destination of the vehicle), the base station sends a message to the vehicle""s destination in order to indicate the vehicle""s impending arrival. The message can be via telephone, pager, computer modem or other known mediums of communication.
Upon receipt of the message, a user at the destination can prepare for the vehicle""s impending arrival. As an example, if the vehicle is a school bus, the base station can send a message via telephone to each student assigned to the school bus, when the school bus is within five minutes of the respective student""s home. Consequently, the students do not need to wait at the pick-up point (sometimes in adverse weather conditions) for an extended length of time when the school bus is late relative to the school bus"" normal schedule.
Other applications include using the tracking system to determine the location of delivery vehicles such as overnight letter carriers or armored trucks, which typically carry valuable cargo. The position of the delivery vehicle can be monitored by the base station, and the destination can be notified when the vehicle will arrive. Furthermore, the tracking system can provide an extra level of security when the vehicle is hijacked or stolen. By monitoring the location of the vehicle at the base station, the travel data communicated to the base station can be used to help law enforcement personnel locate the vehicle.
However, the transmissions from the vehicle to the base station create a number of problems. For example, the transmission signals can be intercepted by unauthorized users. These users may then use the travel data in undesirable ways, which are contrary to the interest of the authorized users. As an example, the travel data of an armored truck may be intercepted by an unauthorized user to determine the truck""s location in order to facilitate a hijacking of the truck.
Although the transmission signals may be encrypted, encryption is oftentimes insufficient to adequately protect the privacy of the signals being transmitted. As known in the art, if an unauthorized user obtains enough samples, then the user can break the encryption and interpret the signals. A user can gather enough sample points to break the encryption by simply monitoring a location where the vehicle normally travels or by following the vehicle while the vehicle is transmitting data. Therefore, the transmissions from the vehicle to the base station create security concerns for the authorized users of the tracking system.
In addition, another problem associated with the communication of travel data from a vehicle to a base station is the large number of data bits required to communicate the vehicle""s position. In this regard, communication is oftentimes achieved over cellular channels, and cellular providers normally bill based on the number of data packets transmitted. Each data packet typically enables the communication of a finite number of data bits. For example, many current cellular communication systems transmit thirty-two bits of data in each data packet. Accordingly, each transmission of the vehicle""s location requires more than one data packet, since each coordinate value associated with the GPS system is typically thirty-two bits long and since two coordinates values are transmitted for each location. It is desirable for the length of the data message communicating the vehicle""s location to be reduced so that communication expenses can be minimized. If each coordinate value can be reduced to sixteen bits or less, then the two coordinate values indicating the vehicle""s position can be transmitted with one data packet, as long as the data packet allows at least thirty-two bits of data.
Thus, a heretofore unaddressed need exists in the industry for a tracking system and method for safely transmitting a vehicle""s location and for reducing a number of data bits used to indicate the vehicle""s position.
The present invention overcomes the inadequacies and deficiencies of the prior art as discussed herein. The present invention provides a system and method for safely and efficiently communicating vehicle tracking information to a base station that notifies a user of a particular location of a vehicle.
In a broad sense, the present invention utilizes a sensor, a translation mechanism, and a monitoring mechanism. The sensor determines position values that represent a location of a vehicle relative to a first reference point. The translation mechanism receives the position values and translates the position values into translated values representing a location of the vehicle relative to a second reference point. The translation mechanism then transmits the translated values to a monitoring mechanism that tracks the vehicle based on the translated values received from the translation mechanism.
In accordance with another feature of the present invention, the translation mechanism mathematically combines the coordinate values of the second reference point with the position values to determine the translated values. In order to determine the vehicle""s position relative to the first reference point, the monitoring mechanism mathematically combines the second reference point with the translated values received from the translation mechanism.
In accordance with another feature of the present invention, the location of the second reference point can be changed to further frustrate and confuse attempts to interpret the data transmissions.
The present invention can also be viewed as providing a method for communicating vehicle tracking information. Briefly described, the method can be broadly conceptualized by the following steps: determining coordinate values that indicate a location of a vehicle relative to a first reference point; translating the coordinate values to provide new coordinate values that indicate a location of the vehicle relative to a second reference point; transmitting the new coordinate values to a monitoring mechanism monitoring the vehicle; and determining a location of the vehicle relative to a predetermined location based on the new coordinate values.
The present invention has many advantages, a few of which are delineated hereafter, as mere examples.
An advantage of the present invention is that attempts by unauthorized users to interpret data transmissions associated with a vehicle tracking system are frustrated and confused.
Another advantage of the present invention is that the amount data transmitted in a vehicle tracking system can be reduced.
Another advantage of the present invention is that costs associated with a vehicle tracking system can be reduced.
Another advantage of the present invention is that it is simple in design and easily implemented.
Another advantage of the present invention is that it can be implemented in software, hardware, or a combination thereof.
Other features and advantages of the present invention will become apparent to one skilled in the art upon examination of the following detailed description, when read in conjunction with the accompanying drawings. It is intended that all such features and advantages be included herein within the scope of the present invention, as is defined by the claims.